Subject: FW: [PWE3] RE: general comments on draft-muley-dutta draft

From: "MULEY Praveen" <[email-masked]>
Date: Wed, 2 Jan 2008 13:26:51 -0600

Roman :
    Thanks for your detail review and comments. We will accommodate
these in our next version of draft.

Thanks,
Praveen 

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]
Sent: Monday, December 31, 2007 8:59 AM
To: [email-masked]
Subject: [PWE3] RE: general comments on draft-muley-dutta draft

Few comments that may help in clarification of the language in
draft-muley-dutta:
( some of these points may have been discussed earlier but I did not see
it so I am reading the current document as it is..)I do not see comments
as purely stylistic as my intention is to have a text clear and not open
to interpretations where not intended.

----------
Section 2 Motivation 

In the following paragraph: 
" In the absence of faults, all PWs are operationally UP both locally 
   and remotely and a PE node needs to select a single PW to forward 
   user packets to. >>>This is referred to as the active PW. All other
PWs 
   will be in standby and must not be used to forward user packets.<<<" 

I propose to change not a  very precise >>>This is ...."  into " The PW
into which user packets will be forwarded will be the active PW.
 All other PWs will be passive or in standby mode and must not be used
to forward user packets."

I propose to rework the following sentence:

" In order for both ends of the service to select the same PW for 
   forwarding user packets, >>> it is proposed that a PE node
communicates a 
   new status bit to indicate the forwarding state of a PW to its peer 
   PE node."

Into something like this

"....  it is proposed that a PE node communicates a new status bit to
its peer 
   PE node to indicate the forwarding state of a PW ."
Or

"....  it is proposed that a PE node communicates to its peer 
   PE node a new status bit to indicate the forwarding state of a PW ."

Section 3 - Terminology
-------
Is
"Active PW: An UP PW used for forwarding user traffic. "

Change to 

" Active PW: An UP PW that is used for forwarding user traffic."

-----------
Is
" PW Endpoint: A PE where a PW terminates on an NSP e.g. A SS-PW PE, an 
           MS-PW T-PE, or a VPLS MTU or PE-r. "

I propose to use some kind of designation for the PW endpoint at the
risk of having too many of them in Pwe documents - at least as a macro
for "A SS-PW PE, an MS-PW T-PE, or a VPLS MTU or PE-r" in this document
- for example E-PE or even better - END-PE and use it consistently
across the document.

-----------

Section 4: Modes of Operation

Is:
"There are two modes of operation for the use of the PW preferential
  forwarding status bits:  "

I suggest:

"There are two modes of operation (in which) the PW preferential
  forwarding status bits COULD ( SHALL ) be used:  "

 ---------

Section 4.1  Independent mode:

Is:
PW endpoint nodes independently select which PW they intend to make 
   active and which PWs they intend to make standby. They advertise the 
   corresponding Active/Standby forwarding state for each PW. Each PW 
   endpoint compares local and remote status and uses the PW that is 
    operationally UP at both endpoints and that shows Active states at 
   both the local and remote endpoint.  

I suggest adding END-PE designations:

PW endpoint nodes (END-PE)independently select which PW they intend to
make active and which PWs they intend to make standby. They advertise
the corresponding Active/Standby forwarding state for each PW to
corresponding Nodes ( END-PEs). Each PW endpoint (END-PE) compares local
and remote status and uses the PW that is operationally UP at both
endpoints and that shows Active states at   both the local and remote
endpoint (END-PE).  

-----------

Is:

" In steady state, a PE will always find an Active PW. However, it ..."

"Steady state" - term is not referred to in the document thus it may be
open to interpretations.

But this may be obvious... So I do not feel strongly about it.
--------

Section 4.2 Master/slave mode:

Is:

One endpoint node of the redundant set of PWs is designated the 
   Master and is responsible for selecting which PW both endpoints must 
   use to forward user traffic.

Suggested:

One endpoint node (END-PE) of the redundant set of PWs is designated the

   Master [the other end point ( END-PE) is selected a s a slave] and is
responsible for selecting which PW endpoints (Master node and slave
node) must  use to forward user traffic.

------
Is:
This status is indicated to the Slave node by setting the preferential
forwarding 
   status bit in the status bit TLV to Active. 

Would this addition clarify the proposal:
"This status is indicated to the Slave node by setting the preferential
forwarding  status bit in the status bit TLV to Active (Status field in
PWE Status TLV in LDP Notification Message".

----------
IS:

"One endpoint of the PW, the Master, actively selects which PW to 
   activate and uses it for forwarding user traffic. This status is 
   indicated to the Slave node by setting the preferential forwarding 
   status bit in the status bit TLV to Active. >>>>It does forward user
traffic to any other of the PW's in the redundant set to the slave 
   node and indicates this by setting the preferential forwarding status

   bit in the status bit TLV to Standby for those PWs. <<<< The master
node 
   MUST ignore any Active/Standby status bits received from the Slave 
   nodes.  

I refer to the sentence between >>>.. <<<
 
It does not seem clear to me - " It does forward.." refers to - the
Master ?
If yes, better to write it as " The Master node forwards user traffic..
" 

As well, the whole sentence needs some reworking as it seems  confusing:
Maybe this would be OK:

" The Master node forwards user (may ? has or should ?) traffic to any (
one of, any or all ?) (delete -other of) the PW's in the redundant set
(available on the master node)  to the slave node and indicates this (
indicates this to whom - to the slave node in the notification message)
assume) by setting the preferential forwarding status bit in the status
bit TLV to Standby for those PWs."

-----
The same section:

Is:

The Slave endpoint(s) are required to act on the status bits received 
   from the Master. When the received status bit transitions from Active

   to Standby, a Slave node MUST stop forwarding over the previously 
   active PW. 

We should add:
The Slave endpoint(s) are required to act on the status bits received 
   from the Master. When the received status bit transitions from Active

   to Standby, a Slave node MUST stop forwarding over the previously 
   active PW. >> A slave node, upon changing  state from active to
standby must initiate AC down signaling to directly attached AC end node
or PW if this is SS-PE<<<<

---------

Section 5.1

Is:
Each endpoint compares the updated local and remote status and 
   effectively activates the PW which is

"effectively" needs either an explanation or is redundant 

----
Thx
rmk

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